Abstract: A continuously wire electrical explosion spraying device was developed to prepare Mo coating on the inner surface of stainless steel tube with variation of energy density. The surface morphology of coating and the bonding with the substrate were analyzed. The results show that the formation of coating was mainly caused by impact of liquid metal of explosion products. With increasing of energy density, the accumulated liquid coating changed to liquid spraying coating. When the energy density was greater than 350 J/mm³,the size of liquid drop reduced but the temperature and velocity of liquid drop increased. In this case, the smooth spraying coating with larger bonding strength was formed, but the coating deposition rate decreased due to more vapor particles produced.